#define  _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main() {
	int sum = 20;
	int num = 0;
	for (sum; sum >0; sum--) {
		num++;
		if (num % 2 == 0) {
			num++;
		}
	}
	printf("%d", num);
	return 0;
}